Fix for 4265 : Unit test AssuredReplicationServerTest#testSafeDataLevelOne suffers randoms failures

The failures are caused by a real but very rare  and minor bug.
When a Directory Server connects to a Replication Server at the same time a change is generated by
another server and this change is the first to be sent to the directory server it can be sent
with the wrong assured status.
This cause no harm in a real deployment but was causing test failure in our case.

This is fixed by using the message from the message queue rather than from the replication log